It is often advantageous to determine actual engine idling speed particularly for internal combustion engines used for powering vehicular travel in order to detect and record any changes that may be occurring in order to provide a reliable basis for operation of systems, such as automatic clutch systems, that may use engine idling speed as a factor in their mode of operation.
It is well known that variety of factors including as faulty parts, wear, variations in temperature and changes in combustion may cause engine idling speed to increase or decrease over a period of time and for such reason it is desirable to monitor and record engine idling speed so that it may be used as a reliable and accurate basis for control of other functions where required.
Although a variety of engine idling speed control systems have been devised in the past, none, excepting the sensing system disclosed in U.S. Pat. No. 4,359,894, stored the value of engine idling speed being sensed and even here the value is only stored when it is equal to or less than the value previously stored when the engine speed signal is proportional to engine speed or when the value is equal to or greater than the previously stored value when the engine speed signal is inversely proportional to the engine speed in addition to the fact that it relies solely upon monitoring the most closed throttle plate position rather than actual engine speed itself.
In view of the above, a need has existed to provide a system for monitoring and recording engine idling speed on a continuous basis in order to provide an advantageous basis for improving shifting for semi-automatic and automatic transmissions or the like and for other systems which use engine idling speed in their operation as well as for providing a visual display of engine idling speed as a means of indicating any change that may be occurring so that corrective adjustments may be made if desired.